1. Field of the Present Invention
The present invention relates to a technology for collecting attribute-information of an information processing apparatus to be monitored in a system for monitoring the information processing apparatus via a network.
2. Description of the Related Art
Conventionally, a system for monitoring an information processing apparatus via a network, such as a network monitoring system or a server monitoring system, obtains a name or an identifier of a management attribute installed in the monitoring system in advance or set by a system administrator from an apparatus, such as a communication apparatus or an information terminal to be monitored (hereinafter, “node”), using a protocol for monitoring the network, and judges whether the attribute value is valid (e.g. whether the attribute value does not exceed a threshold value) or identifies points of failure.
A widely-used example of the protocol for monitoring the network, which is used by the network monitoring system, is a simple network management protocol (SNMP). The SNMP is a protocol that allows a network monitoring system to collect information from a node being a monitoring target and to change the setting of each of the nodes (see, for example, J. Case, M. Fedor, M. Schoffstall, J. Davin, “A simple Network Management Protocol (SNMP)”, [online], May 1990, [retrieved on 19 Nov. 2005].
With the SNMP, information of nodes is managed in units called objects. Each of the objects stores therein an attribute value that corresponds to the attribute of the object. The objects are classified, according to the type of each object, into a plurality of type groups that are hierarchized. Also, each of the objects is identified-using an identifier called an object ID (hereinafter “OID”). An OID is made up of values connected by periods “.” that correspond to hierarchy levels, and different values are assigned to different type groups and different objects.
The SNMP uses a concept called “tables” which are used for managing a plurality of objects of the same type within a type group. A table includes a plurality of groups called entries each of which is made up of a plurality of predetermined objects. The number of entries included in a table depends on each of the nodes and may increase or decrease with changes in the hardware configuration. To each of the entries, an index for identifying the entry is assigned. Each of the objects belonging to an entry is identified by an index added to the OID so that it can be recognized to which entry each of the objects belongs. It is determined for each of the type groups whether the objects are managed in the table format.
For example, the OID of a sysName object, which denotes the name of the apparatus itself, is expressed as “1.3.6.1.2.1.1.5.0”. A set of the first seven numerals “1.3.6.1.2.1.1” denotes a “System” group that classifies the information related to the apparatus itself. The following numeral “5” denotes the sysName object. The last numeral “0” is an index for further classifying the sysName object. When the index is “0”, it means that this object is not expressed in the table format and that this object is the only object in the apparatus.
As another example, the OID of an ifErrors object, which denotes the number of packets that had errors in each of the interfaces included in an apparatus, is expressed as “1.3.6.1.2.1.2.2.1.14.n”. A set of the first seven numerals “1.3.6.1.2.1.2” denotes an “Interface” group that classifies the information related to the interface. The following numeral “14” denotes the ifErrors object. The last letter “n” is an index for further classifying the ifErrors object. For example, when the “ifIndex” of Port No. 5 is “5”, the number of packets that had errors in Port No. 5 can be expressed by changing “n” to “5”.
FIG. 20 is a schematic for illustrating a network monitoring system and a node-information collecting method using the SNMP according to a conventional technology. In the network monitoring system, the network monitoring apparatus regularly collects node information from each of the nodes connected to the network being the monitoring target, using a Get command or a GetNext command defined by the SNMP for the purpose of collecting information.
The Get command is a command for specifying an OID of the object to be obtained so as to notify the node and obtaining the specified OID and an attribute value of the object identified with the OID. The GetNext command is a command for specifying an OID so as to notify the node and obtaining an OID that is subsequent to the specified OID in the lexical order and an attribute value of the object identified with the subsequent OID.
For example, as shown in Method 1 in FIG. 20, when a Get command is executed with the OID “1.3.6.1.2.1.2.2.1.3.1” being specified, the node returns the OID “1.3.6.1.2.1.2.2.1.3.1” and its attribute value “6”. As another example, as shown in Method 2 in FIG. 20, when a GetNext command is issued with the OID “1.3.6.1.2.1.2.2.1.3” being specified, the node returns the OID “1.3.6.1.2.1.2.2.1.3.1” and its attribute value “6”.
To provide further information, as for objects that are managed in the table format, because the number of entries included in a table depends on each of the nodes, the network monitoring apparatus is not able to recognize the OIDs in advance. Consequently, when an attribute value of such an object is to be obtained, it is not possible to obtain attribute values of all the objects using a Get command, because a Get command requires that the OIDs be specified directly. Thus, attribute values of unknown objects are obtained by sequentially and repeatedly obtaining an OID that is subsequent to an OID specified as a reference, using a GetNext command.
FIG. 21 is a schematic for explaining how node information is collected using a GetNext command. For example, the network monitoring apparatus executes a GetNext command by specifying the OID “1.3.6.1.2.1.2.2.1.3”, and thus obtains the OID “1.3.6.1.2.1.2.2.1.3.1” and its attribute value “6”. Subsequently, the network monitoring apparatus executes a GetNext command by specifying the obtained OID “1.3.6.1.2.1.2.2.1.3.1”, and thus obtains the OID “1.3.6.1.2.1.2.2.1.3.5” and its attribute value 6. Further, the network monitoring apparatus executes a GetNext command by specifying the obtained OID “1.3.6.1.2.1.2.2.1.3.5” and, and thus obtains the OID “1.3.6.1.2.1.2.2.1.3.7” and its attribute value “6”.
With the arrangements of the node-information collecting method according to the conventional technique, which takes it into account that OIDs change depending on the configurations and the state of the nodes, because each of the GetNext commands is executed by sequentially specifying an OID at a time, the network monitoring apparatus and the network being the monitoring target need to communicate with each other every time the command is executed. The problems with this conventional method are that a load to the monitoring target network is increased and that the processing time required for collecting the apparatus information is long.